Bone conduction hearing device having acoustic feedback reduction system

ABSTRACT

A bone anchored hearing device, comprises: a housing, a sound input element positioned in the housing configured to receive sound signals, and a transducer positioned in the housing configured to generate vibrations representative of the sound signals received by the sound input device.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.61/041,185, entitled “Bone Conduction Devices For The Rehabilitation OFHearing Disorders,” filed Mar. 31, 2008. This application is herebyincorporated by reference herein.

BACKGROUND

1. Field of the Invention

The present invention relates generally to bone anchored hearingdevices, and more particularly, to bone anchored hearing devices havinga feedback reduction system.

2. Related Art

Hearing loss, which may be due to many different causes, is generally oftwo types, conductive or sensorineural. In many people who areprofoundly deaf, the reason for their deafness is sensorineural hearingloss. This type of hearing loss is due to the absence or destruction ofthe hair cells in the cochlea which transduce acoustic signals intonerve impulses. Various prosthetic hearing implants have been developedto provide individuals who suffer from sensorineural hearing loss withthe ability to perceive sound. One such prosthetic hearing implant isreferred to as a cochlear implant. Cochlear implants use an electrodearray implanted in the cochlea of a recipient to bypass the mechanismsof the ear. More specifically, an electrical stimulus is provided viathe electrode array directly to the cochlea nerve, thereby causing ahearing sensation.

Conductive hearing loss occurs when the normal mechanical pathways toprovide sound to hair cells in the cochlea are impeded, for example, bydamage to the ossicular chain to ear canal. However, individuals whosuffer from conductive hearing loss may still have some form of residualhearing because the hair cells in the cochlea are may remain undamaged.

Individuals who suffer from conductive hearing loss are typically notcandidates for a cochlear implant due to the irreversible nature of thecochlear implant. Specifically, insertion of the electrode array into arecipient's cochlea exposes the recipient to risk of the destruction ofthe majority of hair cells within the cochlea. The destruction of thecochlea hair cells results in the loss of all residual hearing by therecipient.

Rather, individuals suffering from conductive hearing loss typicallyreceive an acoustic hearing aid, referred to as a hearing aid herein.Hearing aids rely on principles of air conduction to transmit acousticsignals through the outer and middle ears to the cochlea. In particular,a hearing aid typically uses an arrangement positioned in therecipient's ear canal to amplify a sound received by the outer ear ofthe recipient. This amplified sound reaches the cochlea and causesmotion of the cochlea fluid and stimulation of the cochlea hair cells.

Unfortunately, not all individuals who suffer from conductive hearingloss are able to derive suitable benefit from hearing aids. For example,some individuals are prone to chronic inflammation or infection of theear canal and cannot wear hearing aids. Other individuals have malformedor absent outer ear and/or ear canals as a result of a birth defect, oras a result of medical conditions such as Treacher Collins syndrome orMicrotia. Furthermore, hearing aids are typically unsuitable forindividuals who suffer from single-sided deafness (total hearing lossonly in one ear). Cross aids have been developed for single sided deafindividuals. These devices receive the sound from the deaf side with onehearing aid and present this signal (either via a direct electricalconnection or wirelessly) to a hearing aid which is worn on the oppositeside. The disadvantage of this technology is the need for the individualto wear two hearing aids and suffer the complications of hearing aiduse.

When an individual having fully functional hearing receives an inputsound, the sound is transmitted to the cochlea via two primarymechanisms: air conduction and bone conduction. As noted above, hearingaids rely primarily on the principles of air conduction. In contrast,other devices, referred to as bone conduction devices, relypredominantly on vibration of the bones of the recipients skull toprovide acoustic signals to the cochlea.

Those individuals who cannot derive suitable benefit from hearing aidsmay benefit from bone conduction devices. Bone conduction devicesfunction by converting a received sound into a mechanical vibrationrepresentative of the received sound. This vibration is then transferredto the bone structure of the skull, causing vibration of the recipient'sskull. This skull vibration results in motion of the fluid of thecochlea. Hair cells inside the cochlea are responsive to this motion ofthe cochlea fluid, thereby generating nerve impulses resulting in theperception of the received sound.

A known alternative to a normal air conduction hearing aid is a boneconduction hearing aid which uses a hearing aid to drive a vibratorwhich is pushed against the skull via a mechanism, such as glasses orwire hoops. These devices are generally uncomfortable to wear and, forsome recipients, are incapable of generating sufficient vibration toaccurately present certain received sounds to a recipient.

SUMMARY

In one aspect of the invention, a bone anchored hearing device isprovided. The device comprises: a housing, a sound input elementpositioned in the housing configured to receive sound signals, and atransducer positioned in the housing configured to generate vibrationsrepresentative of the sound signals received by the microphone, whereinthe generated vibrations are directed along a displacement axis, andwherein the sound input element is substantially aligned with thedisplacement axis, such that vibrations induced to the sound inputelement are reduced.

In another aspect of the invention, a method of reducing the acousticfeedback in a bone conduction hearing device is provided. The method,comprises: positioning a transducer in the bone conduction hearingdevice such that the transducer generates vibrations along onedisplacement axis, and positioning a sound input element in the boneconduction hearing device such that it is substantially aligned with thedisplacement axis, such that vibrations induced to the sound inputelement are reduced.

In another aspect of the invention, a system for reducing acousticfeedback in a bone anchored hearing device is provided. The systemcomprises: a transducer positioned within in the bone conduction hearingdevice such that the transducer generates vibrations along onedisplacement axis, and a sound input element positioned in the boneconduction hearing device and substantially aligned with thedisplacement axis, such that the vibrations induced to the sound inputelement are reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

Illustrative embodiments of the present invention are described hereinwith reference to the accompanying drawings, in which:

FIG. 1 is a perspective cutaway view of a human ear and a boneconduction device implanted behind the ear in which embodiments of thepresent invention may be advantageously implemented;

FIG. 2A is a functional block diagram of an embodiment of a boneconduction device in accordance with one embodiment of the presentinvention;

FIG. 2B is a more detailed functional block diagram of the boneconduction device of FIG. 2A in accordance with one embodiment of thepresent invention;

FIG. 3 is an exploded view of an embodiment of a bone conduction devicein accordance with one embodiment of FIG. 2B in accordance with oneembodiment of the present invention;

FIG. 4A is a schematic diagram of a bone conduction device with aninternal sound input element suspended from the housing via a vibrationdampening coupling member;

FIG. 4B is a top perspective view of a bone conduction device with asound input element mounted externally to said housing via a vibrationdampening coupling member;

FIG. 4C is a cross sectional view of the flexible connector of FIG. 4Btaken along line 4C-4C in FIG. 4B;

FIG. 4D is a schematic diagram of a bone conduction device with aninternal sound input element suspended from the housing via a pluralityof vibration dampening coupling member;

FIG. 5A is a schematic diagram of a bone conduction device with amicrophone positioned such that a diaphragm of the microphone isoriented substantially parallel to the transducer vibrations inaccordance with one embodiment of the present invention;

FIG. 5B is a schematic diagram showing the relative orientation of adiaphragmatic microphone and its concomitant vibration axis and thedisplacement axis of the transducer, in accordance with one embodimentof the present invention;

FIG. 5C is a simplified diagram of a dynamic microphone in accordancewith one embodiment of the present invention;

FIG. 5D is a simplified diagram of a condenser microphone in accordancewith one embodiment of the present invention;

FIG. 6A is a system block diagram of a bone conduction device with abone anchored housing and a separate microphone housing;

FIG. 6B is a perspective view of a bone conduction device having amicrophone separated from the bone anchored housing; and

FIG. 7 is a flow chart illustrating the implantation of the boneconduction device of FIGS. 6A and 6B in accordance with one embodimentof the present invention.

DETAILED DESCRIPTION

Embodiments of the present invention are generally directed to a boneconduction device for converting a received acoustic sound signal into amechanical force for delivery to a recipient's skull. The boneconduction device includes a housing having a sound input component,such as microphone, to receive the acoustic sound signal, an electronicsmodule configured to generate an electrical signal representing theacoustic sound signal, and a transducer to convert the electrical signalinto a mechanical force for delivery to the recipient's skull. Thetransducer is configured to generate vibrations substantially along onedisplacement axis.

FIG. 1 is a perspective view of embodiments of a bone conduction device100 in which embodiments of the present invention may be advantageouslyimplemented. In a fully functional human hearing anatomy, outer ear 101comprises an auricle 105 and an ear canal 106. A sound wave or acousticpressure 107 is collected by auricle 105 and channeled into and throughear canal 106. Disposed across the distal end of ear canal 106 is atympanic membrane 104 which vibrates in response to acoustic wave 107.This vibration is coupled to oval window or fenestra ovalis 110 throughthree bones of middle ear 102, collectively referred to as the ossicles111 and comprising the malleus 112, the incus 113 and the stapes 114.Bones 112, 113 and 114 of middle ear 102 serve to filter and amplifyacoustic wave 107, causing oval window 110 to articulate, or vibrate.Such vibration sets up waves of fluid motion within cochlea 115. Suchfluid motion, in turn, activates cochlear hair cells (not shown).Cochlear hair cells come in two anatomically and functionally distincttypes: the outer and inner hair cells. Activation of one or more typesof these hair cells causes appropriate nerve impulses to be transferredthrough the spiral ganglion cells and auditory nerve 116 to the brain(not shown), where they are perceived as sound.

FIG. 1 also illustrates the positioning of bone conduction device 100relative to outer ear 101, middle ear 102 and inner ear 103 of arecipient of device 100. As shown, bone conduction device 100 may bepositioned behind outer ear 101 of the recipient.

In the embodiments illustrated in FIG. 1, bone conduction device 100comprises a housing 125 having a microphone 126 positioned therein orthereon. Housing 125 is coupled to the body of the recipient viacoupling 140. As described below, bone conduction device 100 maycomprise a sound processor, a transducer, transducer drive componentsand/or various other electronic circuits/devices.

In accordance with embodiments of the present invention, an anchorsystem (not shown) may be implanted in the recipient. As describedbelow, the anchor system may be fixed to bone 136. In variousembodiments, the anchor system may be implanted under skin 132 withinmuscle 134 and/or fat 128. In certain embodiments, a coupling 140attaches device 100 to the anchor system.

A functional block diagram of one embodiment of bone conduction 100,referred to as bone conduction device 200, is shown in FIG. 2A. In theillustrated embodiment, a sound 207 is received by a sound input element202. In some embodiments, sound input element 202 is a microphoneconfigured to receive sound 207, and to convert sound 207 into anelectrical signal 222. As described below, in other embodiments sound207 may received by sound input element 202 as an electrical signal.

As shown in FIG. 2A, electrical signal 222 is output by sound inputelement 202 to an electronics module 204. Electronics module 204 isconfigured to convert electrical signal 222 into an adjusted electricalsignal 224. As described below in more detail, electronics module 204may include a sound processor, control electronics, transducer drivecomponents, and a variety of other elements.

As shown in FIG. 2A, a transducer 206 receives adjusted electricalsignal 224 and generates a mechanical output force that is delivered tothe skull of the recipient via an anchor system 208 coupled to boneconduction device 200. Delivery of this output force causes one or moreof motion or vibration of the recipients skull, thereby activating thehair cells in the cochlea via cochlea fluid motion.

FIG. 2A also illustrates a power module 210. Power module 210 provideselectrical power to one or more components of bone conduction device200. For ease of illustration, power module 210 has been shown connectedonly to interface module 212 and electronics module 204. However, itshould be appreciated that power module 210 may be used to supply powerto any electrically powered circuits/components of bone conductiondevice 200.

Bone conduction device 200 further includes an interface module 212 thatallows the recipient to interact with device 200. For example, interfacemodule 212 may allow the recipient to adjust the volume, alter thespeech processing strategies, power on/off the device, etc. Interfacemodule 212 communicates with electronics module 204 via signal line 228.

In the embodiment illustrated in FIG. 2A, sound pickup device 202,electronics module 204, transducer 206, power module 210 and interfacemodule 212 have all been shown as integrated in a single housing,referred to as housing 225. However, it should be appreciated that incertain embodiments of the present invention, one or more of theillustrated components may be housed in separate or different housings.Similarly, it should also be appreciated that in such embodiments,direct connections between the various modules and devices are notnecessary and that the components may communicate, for example, viawireless connections.

FIG. 2B provides a more detailed view of bone conduction device 200 ofFIG. 2A. In the illustrated embodiment, electronics module 204 comprisesa sound processor 240, transducer drive components 242 and controlelectronics 246. As explained above, in certain embodiments sound inputelement 202 comprises a microphone configured to convert a receivedacoustic signal into electrical signal 222. In other embodiments, asdetailed below, sound input element 202 receives sound 207 as anelectrical signal.

In embodiments of the present invention, electrical signal 222 is outputfrom sound input element 202 to sound processor 240. Sound processor 240uses one or more of a plurality of techniques to selectively process,amplify and/or filter electrical signal 222 to generate a processedsignal 224A. In certain embodiments, sound processor 240 may comprisesubstantially the same sound processor as is used in an air conductionhearing aid. In further embodiments, sound processor 240 comprises adigital signal processor.

Processed signal 226A is provided to transducer drive components 242.Transducer drive components 242 output a drive signal 224B, totransducer 206. Based on drive signal 224B, transducer 206 provides theoutput force to the skull of the recipient.

For ease of description the electrical signal supplied by transducerdrive components 242 to transducer 206 has been referred to as drivesignal 224B. However, it should be appreciated that processed signal224B may comprise an unmodified version of processed signal 224A.

As noted above, transducer 206 generates an output force to the skull ofthe recipient via anchor system 208. As shown in FIG. 2B, anchor system208 comprises a coupling 260 and an implanted anchor 262. Coupling 260may be attached to one or more of transducer 206 or housing 225. Forexample, in certain embodiments, coupling 260 is attached to transducer206 and vibration is applied directly thereto. In other embodiments,coupling 260 is attached to housing 225 and vibration is applied fromtransducer 206 through housing 225.

As shown in FIG. 2B, coupling 260 is coupled to an anchor implanted inthe recipient, referred to as implanted anchor 262. As explained withreference to FIG. 3, implanted anchor 262 provides an element thattransfers the vibration from coupling 260 to the skull of the recipient.

As noted above, a recipient may control various functions of the devicevia interface module 212. Interface module 212 includes one or morecomponents that allow the recipient to provide inputs to, or receiveinformation from, elements of bone conduction device 200.

As shown, control electronics 246 may be connected to one or more ofinterface module 212, sound pickup device 202, sound processor 240and/or transducer drive components 242. In embodiments of the presentinvention, based on inputs received at interface module 212, controlelectronics 246 may provide instructions to, or request informationfrom, other components of bone conduction device 200. In certainembodiments, in the absence of user inputs, control electronics 246control the operation of bone conduction device 200.

FIG. 3 illustrates an exploded view of one embodiment of bone conduction200 of FIGS. 2A and 2B, referred to herein as bone conduction device300. As shown, bone conduction device 300 comprises an embodiment ofelectronics module 204, referred to as electronics module 304. Asexplained above, included within electronics module 304 are a soundprocessor, transducer drive components and control electronics. For easeof illustration, these components have not been illustrated in FIG. 3.

In the illustrated embodiment, electronics module 304 includes a printedcircuit board 314 (PCB) to electrically connect and mechanically supportthe components of electronics module 304. Attached to PCB 314 are one ormore sound input elements, shown as microphones 302 to receive a sound.

In the illustrated embodiment, bone conduction device 300 furthercomprises battery shoe 310 for supplying power to components of device300. Battery shoe 310 may include one or more batteries. In certainembodiments, PCB 314 is attached to a connector 376. Connector 376 isconfigured to mate with battery shoe 310. In certain embodiments,connector 376 and battery shoe 310 may be releasably snap-locked to oneanother. Furthermore, in such embodiments, one or more battery connects(not shown) are disposed in connector 376 to electrically connectbattery shoe 310 with electronics module 304.

In the embodiment illustrated in FIG. 3, bone conduction device 300further includes a two-part housing 325, comprising first housingportion 325A and second housing portion 325B. Housing portions 325 areconfigured to mate with one another to substantially seal boneconduction device 300.

In the embodiment of FIG. 3, first housing portion 325A has an openingtherein for receiving battery shoe 310. In such embodiments, batteryshoe protrudes through first housing portion 325A and may be removed orinserted by the recipient. Also in the illustrated embodiment,microphone covers 372 are releasably attached to first housing portion325A. Microphone covers 372 provide a barrier over microphones 302 toprotect microphones 302 from dust, dirt or other debris.

Bone conduction device 300 further includes an embodiment of interfacemodule 212, referred to herein as interface module 312. Interface module312 is configured to provide or receive user inputs from the recipient.

Also as shown in FIG. 3, bone conduction device 300 comprises anembodiment of transducer 206, referred to as transducer 306. Transducer306 generates an output force that causes movement of the cochlea fluidso that a sound may be perceived by the recipient. The output force mayresult in mechanical vibration of the recipient's skull, or in physicalmovement of the skull about the neck of the recipient. As noted above,in certain embodiments, bone conduction device 300 delivers the outputforce to the skull of the recipient via an anchor system 308. Anchorsystem 308 comprises a coupling 360 and implanted anchor 362. In theembodiment illustrated in FIG. 3, coupling 360 is configured to beattached to second housing portion 325B. As such, in this embodiment,vibration from transducer 306 is provided to coupling 360 throughhousing 325B. In the embodiment shown in FIG. 3, an opening 368 isprovided in second housing portion 325B. A screw (not shown) may beinserted through opening 368 to attach transducer 306 to coupling 360.In such embodiments, an O-ring 380 may be provided to seal opening 368around the screw.

As noted above, anchor system 308 includes implanted anchor 362.Implanted anchor 362 comprises a bone screw 366 implanted in the skullof the recipient and an abutment 364. In an implanted configuration,screw 366 protrudes from the recipient's skull through the skin.Abutment 364 is attached to screw 366 above the recipient's skin. Inother embodiments, abutment 364 and screw 366 may be integrated into asingle implantable component. Coupling 360 is configured to bereleasably attached to abutment 364 to create a vibratory pathwaybetween transducer 306 and the skull of the recipient.

In alternative embodiments of the present invention, bone conductiondevice 300 may comprise one or more additional sound input element. Forexample, bone conduction device 300 may comprises an electrical input.In such embodiments, the electrical input is configured to connectdevice 300 to external equipment and receive an electrical sound signaldirectly therefrom. The electrical input may permit bone conductiondevice 300 to be connected to, for example, FM hearing systems, MP3players, televisions, mobile phones, etc.

In still other embodiments, a further sound input element in the form ofa telecoil may be integrated in, or connected to, bone conduction device300. The telecoil permits bone conduction device 300 to receive inputsignals from, for example, a telephone or other similar device.

FIG. 4A illustrates one embodiment of bone conduction device 200,depicted as bone conduction device 400, which includes a housing 402 anda coupler 404 for removeably attaching the housing 402 to an anchor,such as anchor 262 (FIG. 2B). In this embodiment, the housing 402includes, among other components, a microphone or sound input element406 and a transducer 408. Additionally, the housing may include a soundprocessor, an electronics module, a power source and an interface (eachof each is not shown), or any other suitable component, as describedherein. The sound input element, as described above, receives soundwaves, which are sent to the sound processor. Sound processor in turnmay amplify or alter the signal and send this altered signal to thetransducer to impart vibrations to the anchor.

In one embodiment, sound input element 406 is suspended from the housingor coupled to any other suitable portion of the bone anchored device 400using flexible shaft or vibration dampening coupling member 410. Byattaching the sound input element in this manner, the sound inputelement may be isolated from the mechanical vibrations generated by thetransducer, thus reducing feedback through the sound input element. Inother words, the recipient of the bone conduction device will havefeedback percept substantially reduced or eliminated.

In one embodiment, the sound input element is mounted internally ofhousing 402. The coupling member may be a rubber sleeve or otherconfiguration that is configured to allow the sound input element tofrictionally fit therein. In one embodiment, coupling member may becoupled to the sound input element via opening 411 at one end thereofthat allows access to an internal space therein. The sound input elementmay have a diameter slightly larger than opening 411, thus creating asecure, but removable fit for the sound input element. In otherembodiments, the coupling is a connector formed of other suitablematerial, such as silicon, foam and/or any other suitable material orcombination of materials. It is noted that each of these materials mayhave a different spring constant or ability to dampen the vibrations.

In one embodiment, coupling member 410 is coupled to housing 402 atpoint or location 409 and to the sound input element 406 at a point orlocation 413. In this embodiment, the vibrations imparted to the soundimparted to the sound input element are reduced or attenuated from pointor location 409 to point or location 413. In other words, due to thespring constant and the attenuation of the coupling member 410, thevibrations imparted to the sound input element are reduced along thelength of the coupling member 410.

In some embodiments, an additional vibration absorbing material maydisposed between the coupling member and the sound input element tofurther attenuate the vibrations generated by said transducer. Forexample, the coupling member may be a rubber sleeve and the additionalvibration material may be a layer of foam between the coupling and thesound input element.

In one embodiment, the coupling may be a spring or flexible shaft with alow spring constant; however, the spring constant may be any desiredspring constant. The flexible shaft may be formed from metal or plasticor any other suitable material or combination of materials. In thisembodiment, the sound input element may be detachable from the housing,such that the spring constant or stiffness of the flexible shaft may beeasily changeable or selectable as the power levels of the boneconduction device increase or changes. In other words, some springconstants my produce less feedback based on the amplitude of vibrationof the transducer. In this embodiment, the flexible shaft may beselected from a plurality of flexible shafts, each flexible shaft havinga different spring constant or stiffness.

FIG. 4B illustrates one embodiment of bone conduction device 200,depicted as bone conduction device 450. In this embodiment, boneconduction device 450, is substantially similar to device 400; however,sound input element or microphone 452 is mounted externally of housing454 at point or location 458. In this embodiment, vibration dampeningcoupling member is flexible shaft or extension 456 that extendsoutwardly and externally from housing 454. In some embodiments, theshaft 456 has a substantially rectangular cross section, wherein thewidth 459 is substantially greater than its height 461 (FIG. 4C). Thesound input element is coupled to the shaft at point or location 458along the width 459. Such a configuration will enable the shaft toattenuate the vibrations imparted to the sound input element. In thisembodiment, the vibrations imparted to the sound imparted to the soundinput element are reduced or attenuated from or location 455 to point orlocation 458. In other words, due to the spring constant and theattenuation of the shaft 456, the vibrations imparted to the sound inputelement are reduced along the length of the shaft 456. By mounting thesound input element externally in such a manner, feedback is isolated,while allowing for the remaining components to contribute to the massthat is vibrated.

The flexible shaft may be formed from any suitable flexible material,such as rubber, metal, plastic, silicon, and/or any other suitablematerial or the flexible shaft may be a spring, as described above.Disposed at the distal end 458 of the flexible shaft is sound inputelement 452. As with the embodiment of FIG. 4A, an additional vibrationabsorbing material may disposed between the coupling member and thesound input element to further attenuate the vibrations generated bysaid transducer.

Additionally, the sound input element and/or the flexible shaft may bedetachable form the housing, such that the flexible shaft may beselected from a plurality of flexible shafts, each flexible shaft havinga different spring constant or stiffness. Typically, the spring constantis be changed or selected based on the power level of the output of thetransducer; however, any suitable spring constant may be selected. Aswith the above described embodiments, housing 454 generally includes atransducer, an electronics module, an interface and a power module (eachof which is not shown), or any other suitable component, as describedherein.

FIG. 4D illustrates another embodiment of bone conduction device 200,depicted as bone conduction device 470. In this embodiment, boneconduction device 470, is substantially similar to device 400; however,sound input element or microphone 472 is mounted using a plurality ofvibration dampening coupling members 474 a-d. In this embodiment, eachof the vibration dampening coupling members 474 a-d may a springconfigured to reduce or attenuate the vibrations imparted to the soundinput element 472. Each vibration dampening coupling members 474 a-d iscoupled to the housing 476 at a first or location 478 a-d, respectively,and coupled to the sound input element 472 at a second or location 480a-d, respectively. As described above, the vibrations imparted to thesound input element are reduced or attenuated from points or locations478 a-d to points or locations 480 a-d. In other words, due to thespring constant and the attenuation of the shaft 456, the vibrationsimparted to the sound input element are reduced along the length of thevibration dampening coupling members 474 a-d.

As with the embodiments described herein, vibration dampening couplingmembers 474 a-d may be removable and replaceable by other vibrationdampening coupling members having different spring constants orvibration dampening properties. Additionally, each vibration dampeningcoupling members 474 a-d may have different vibration dampeningproperties.

FIG. 5A illustrates one embodiment of bone conduction device 200,depicted as bone conduction device 500. As described above, conductiondevice 500 may include a housing 502 and a coupler 504 for removeablyattaching the housing 502 to an anchor, such as anchor 262 (FIG. 2B). Inthis embodiment, housing 502 includes, among other components, amicrophone or sound input element 506 connected to housing 502 viaextension arms 503, and a transducer 508. As with the above describedembodiments, housing 502 may included, an electronics module, aninterface and a power module (each of which is not shown), or any othersuitable component. The sound input element, as described above,receives sound waves, which are sent to the sound processor. Soundprocessor in turn may amplify or alter the signal and send this alteredsignal to the transducer to impart vibrations to the anchor, along adisplacement axis 510.

In one embodiment, sound input element is positioned and arranged suchthat the moveable component such as a diaphragm 505 of the sound inputelement 506 is configured to vibrate or move due to acoustic sound issubstantially parallel with displacement axis 510. As such, movablecomponent 505 vibrates along a vibration axis that is substantiallyorthogonal with displacement axis 510.

FIG. 5B is a schematic diagram of an exemplary moveable component,diaphragm 558 of a sound input element (not shown) according to oneembodiment of the present invention. As illustrated, movable component558 is mounted such that its sound impinging surface resides in a plane550 which is substantially parallel to displacement axis 510. Byconfiguring the moveable component to be positioned in a plane that issubstantially parallel to the displacement axis, the moveable componentvibrates along a vibration axis 552 that is substantially orthogonalwith displacement axis 510. Thus, the feedback to the sound inputelement is reduced or substantially eliminated.

FIG. 5C illustrates an embodiment of the sound input element for boneconduction device 500 in which the sound input element is shown asdynamic microphone 520. Microphone 520 generally includes a housing 521which encloses a movable component or diaphragm 522, a magnet 524 andinternal wiring 526 that conveys the signal to an amplifier. Themicrophone is configured to operate by having the diaphragm vibrate whencontacted by sound. The diaphragm is attached to and thus, vibratesinternal wiring 526, which is configured as a coil. The movement of thecoil in the magnetic field generates small changes in electricalpressure or voltage, producing a varying current in the coil throughelectromagnetic induction.

FIG. 5D illustrates an embodiment of the sound input element in whichthe sound input element is shown as a condenser microphone 530.Microphone 530 includes a housing 532 which encloses a movable componentor diaphragm 534, a plate 536, an amp 538 and a battery 540. In thisembodiment, diaphragm 534 and plate 536 are oppositely charged such thatwhen moved closer or farther apart, a change in voltage is created. Thisvoltage change or audio signal is then transmitted through wiring 542.Since the change in voltage is typically small (e.g., a millionth of avolt) the signal may be amplified by amp 538. The electrical charge maybe a direct current voltage supplied by battery 540 and may be appliedthrough the same wiring 542 that carries the alternating current voltageof the audio signal.

In some embodiments, the diaphragm of a microphone (e.g., diaphragm 522or 534) may be the moveable component that resides in a plane parallelto the displacement axis 510. By configuring the diaphragm to reside orbe positioned in a plane that is substantially parallel to thedisplacement axis, the diaphragm does not vibrate or the vibrations arereduced when the transducer vibrates. Thus, the feedback to themicrophone will be reduced or substantially eliminated. It is noted thatthe embodiments shown in FIGS. 5C and 5D are merely exemplary and theinvention is not limited to microphones or sound input devices havingthese types of diaphragms.

In one embodiment, transducer 508 is a piezoelectric transducer that isconfigured to control the amplitude of the vibrations in the directionof the displacement axis. The range of the output force of thetransducer 508 may be preselected by the clinician or the recipient toaccommodate certain threshold limits for the recipient's hearing. Theoutput force for the transducer is generally a function of the mass andthe velocity of the transducer 508 moving along the displacement axis510 and the mass of the moving part of the transducer.

In one embodiment, the sound input element is mounted on a movableshaft. The movable shaft is configured to adjust the sound input elementto coincide with the displacement axis. Thus, in this embodiment, aclinician or the recipient may adjust the direction of the movable shaftto improve the sound percept of the recipient.

To achieve the most desired feedback reduction, the recipient's soundpercept any be determined in any suitable manner. For example, therecipient may listen to acoustic sound using the bone conduction device.The sound input element may then be adjusted on the moveable shaft tomore precisely coincide with the displacement axis. This adjustment maybe made manually or using any other suitable device. Once the soundinput element is adjusted, the recipient's sound percept may bedetermined again. This procedure may be repeated until optimum feedbackreduction.

FIGS. 6A and 6B illustrate embodiments of bone conduction device 200,depicted as bone conduction device, in which a sound input element ormicrophone 602 is located in a separate housing, remote from transducer604, to reduce feedback percept by a recipient. By positioning thesecond housing remote from the first housing, transducer vibrations aresubstantially reduced in the sound input element.

In this embodiment, bone conduction device 600 includes a first housing606 and a second housing 608. First housing 606 includes microphone orsound input element 602, a battery 609 and an IR transmitter 610. Secondhousing includes transducer 604, an IR receiver 612, an amp 614,electronics module (e.g., 204), an interface (e.g., 212) and a battery616. It is noted that the components included in each housing are merelyexemplary and each housing may include any components desired, as longas the microphone and the transducer are positioned in separatehousings. The components of bone conduction device 600 operate insubstantially similar manner to those described above.

In some embodiments, first housing 606 is positioned behind the ear orin the ear; however, first housing 606 may be positioned in any suitablearea or place on the recipient. For example, housing 606 may bepositioned in the ear, behind the ear, remotely from the ear or anyother portion of the recipient's body. In another embodiment, housing606 may be implanted or attached to skull 619. Second housing 608 may beremoveably attached to the anchor 617 using a coupling member 615 in asubstantially similar manner as described in the above embodiments or inany other manner described herein.

In this embodiment, bone conduction device 600 operates in a similarmanner as described above; however, the signal 620 from the sound inputelement 602 is sent via an infrared (IR) link 618. By separating thesound input element from the transducer, the microphone is not subjectto the direct vibrations within housing 608 and thus, feedback isreduced. It is noted that communication between the microphone and thetransducer may be any type of wireless communication (e.g., IR, radiofrequency (RF) or any other suitable communications) or thecommunications can be through a wired connection. In the wiredconnection, the device would communicate in a substantially similar todescribed above, except the signal from the microphone would be sent tohousing 608 through an external wire, as discussed below.

It is noted that, in this embodiment, the housings 606 and 608 do notnecessarily need to house the above described components and eachhousing may have positioned therein any of the above described or othersuitable components positioned therein, as long as the sound inputelement and the transducer are separate. For example, in one embodiment,second housing 608 may only include transducer 604 battery, IR receiver612 and a battery 616, while housing 606 contains the remainder of thecomponents.

In some embodiments, as depicted in FIG. 6B, the microphone or soundinput element is connected via wires 622 to housing 608. In thisembodiment, housing 608 may include all the bone conduction hearingdevice components other than sound input element 602. As noted housing606 may be a small platform to which sound input element is attached. Inthis embodiment, feedback may be isolated, while allowing for theremaining components to contribute to the mass that is vibrated.

Microphone 602 may be connected to the ear using clip 624 or in anysuitable manner. For example, microphone may be positioned in or on theear, on any portion of the recipient's head and/or body. Thus, themicrophone may be concealed in a suitable area or may be attached to thebody, ear or head for optimum reception.

FIG. 7 illustrates the general procedure for implanting the boneconduction device 600. As noted in block 702, an anchor (e.g., anchor262) is implanted into the skull of the recipient. As discussed above,the anchor system may be fixed to bone 136. In various embodiments, theanchor system may be implanted under skin 132 within muscle 134 and/orfat 128. In block 704, a housing that includes a transducer (e.g., 608)is coupled to the anchor.

At block 706, a housing that includes a microphone is positionedadjacent the skull of the recipient (e.g., housing 606). As discussedherein, the microphone housing may be placed in the ear, behind the earor any suitable position on the recipient. Communications between thetransducer housing and the microphone housing may then be established,at block 708. such communications may be wireless or wired and may useany type of communication described herein.

Further features and advantages of the present invention are describedin U.S. Provisional Application No. 61/041,185, entitled “BoneConduction Devices For The Rehabilitation OF Hearing Disorders,” filedMar. 31, 2008. This application is hereby incorporated by referenceherein.

While various embodiments of the present invention have been describedabove, it should be understood that they have been presented by way ofexample only, and not limitation. It will be apparent to persons skilledin the relevant art that various changes in form and detail can be madetherein without departing from the spirit and scope of the invention.Thus, the breadth and scope of the present invention should not belimited by any of the above-described exemplary embodiments, but shouldbe defined only in accordance with the following claims and theirequivalents. All patents and publications discussed herein areincorporated in their entirety by reference thereto.

1. A bone anchored hearing device, comprising: a housing; a sound inputelement configured to receive sound signals and comprising a moveablecomponent configured to vibrate along a vibration axis in response tothe received sound signals; and a transducer positioned in said housingconfigured to generate vibrations representative of the sound signalsreceived by said sound input element, wherein the generated vibrationsare directed along a displacement axis that is substantially orthogonalto said vibration axis.
 2. The bone anchored hearing device of claim 1,wherein said moveable component has a substantially planar surface thatis substantially parallel to said displacement axis.
 3. The boneanchored hearing device of claim 1, wherein said transducer is apiezoelectric transducer.
 4. The bone anchored hearing device of claim3, wherein said piezoelectric transducer is configured to control theamplitude of the vibrations in the direction of the displacement axis.5. The bone anchored hearing device of claim 1, wherein the sound inputelement is mounted on a movable shaft.
 6. The bone anchored hearingdevice of claim 3, wherein the movable shaft is configured to adjust thesound input element to coincide with the displacement axis.
 7. The boneanchored hearing device of claim 1, wherein the sound input element is amicrophone.
 8. The bone anchored hearing device of claim 1, wherein themoveable component is a diaphragm.
 9. A method of reducing the acousticfeedback in a bone conduction hearing device, comprising: positioning atransducer in the bone conduction hearing device such that thetransducer generates vibrations along one displacement axis; andpositioning a sound input element in the bone conduction hearing devicesuch that a moveable component of the sound input element vibrates alonga vibration axis that is substantially orthogonal with said displacementaxis.
 10. The method of claim 9, wherein said sound input element ispositioned within a housing of the bone conduction hearing device suchthat said moveable component has a sound impinging surface that issubstantially parallel to said displacement axis.
 11. The method ofclaim 9, wherein said transducer is a piezoelectric transducer.
 12. Themethod of claim 11, wherein said piezoelectric transducer is configuredto control the amplitude of the vibrations in the direction of thedisplacement axis.
 13. The method of claim 9, wherein the sound inputelement is mounted on a movable shaft.
 14. The method of claim 13,further comprising adjusting the movable shaft such that the sound inputelement coincides with the displacement axis.
 15. The method of claim 9,wherein the sound input element is a microphone.
 16. A system forreducing acoustic feedback in a bone anchored hearing device,comprising: a transducer positioned within in the bone conductionhearing device such that the transducer generates vibrations along onedisplacement axis; and a sound input element comprising a moveablecomponent connected to the bone conduction hearing device, said moveablecomponent having a substantially planar sound impinging surface that issubstantially parallel with said displacement axis such that said soundinput device does not substantially respond to vibrations generated bysaid transducer.
 17. The system of claim 16, wherein said moveablecomponent vibrates along a vibration axis that is substantiallyorthogonal to said displacement axis.
 18. The system of claim 16,wherein said transducer is a piezoelectric transducer.
 19. The system ofclaim 18, wherein said piezoelectric transducer is configured to controlthe amplitude of the vibrations in the direction of the displacementaxis.
 20. The system of claim 16, wherein the sound input element ismounted on a movable shaft.
 21. The system of claim 20, wherein themovable shaft is configured to adjust the sound input element tocoincide with the displacement axis.
 22. The system of claim 16, whereinthe sound input element is a microphone.
 23. The system of claim 22,wherein the moveable component is a diaphragm.